1. Field of the Invention
This invention relates to the field of door locks to which an alarm device is electrically coupled, and more particularly to an electric security lock particularly adapted to not only send an electrical signal to the alarm device, but also to be used as an emergency door opening device.
2. Description of the Prior Art
There are several emergency door opening devices, that also have provided an alarm device, now in use. U.S. Pat. No. 3,435,643, entitled Emergency Door Lock Having Alarm Means, issued to Edward C. Pollak and Bennett B. Harman on Apr. 1, 1969, describes one such emergency door opening device, including an alarm device. The alarm device is triggered by a micro electronic switch to which it is electrically coupled. The primary disadvantages of this emergency door opening device is that it is not very compact. Another disadvantage of this device is that it is not very sensitive to tampering by would be thieves because the alarm device is used not for security purposes, but for warning purposes. In order for a security lock to provide maximum security it must be very sensitive to tampering. According to the above patent this emergency door lock permits authorized personnel in possession of an appropriate key to open the door upon which the lock is installed, without sounding the alarm device, while allowing unauthorized personnel to open the same door in an emergency by sounding the alarm device which cannot be disconnected by subsequently closing the door unless the appropriate key is used.
Another emergency door opening device is described in U.S. Pat. No. 3,477,260, entitled Emergency Exit Lock, issued to Walter O. Balducci on Nov. 11, 1969. This emergency door opening device has a slender elogated case structure supporting a latch bolt for movement between projected and retracted positions. The latch bolt is moveable to a retracted position in response to the operation of an external manually operable lever. The lock also includes a latch bolt retractor and hold back mechanism operable independently of the lever in response to operation by a locking cylinder, which is operated by a key. The latter mechanism includes a cam and retractor elements which have coengaging surfaces. The cam element is arranged to move the retractor element in response to the rotation of the locking cylinder in order to move the latch bolt. There is also a hold back mechanism coupled to the retractor elements. This emergency door opening device does not provide an alarm device.
Another emergency door opening device which must be used with an associated alarm device is the subject of U.S. Pat. No. 2,958,215, entitled Safety Lock, issued to Nicholas C. Heyman on Nov. 1, 1960. This emergency door opening device is mechanically similar to the present invention but it does not have an electric activating apparatus for activating an alarm device.
None of the above described emergency door devices provide an electric activating apparatus for activating an alarm device in a remote location. All of these devices are large and cumbersome when mounted on a door; for some uses a more compact emergency door opening device would be far more beneficial than any of the prior art emergency door opening devices.